8272
PIN DESCRIPTION
PIN
CONNECTION
UO
TO
DESCRIPTION
NO.
SYMBOL
PIN
CONNECTION
UO
DESCRIPTION
NO.
SYMBOL
TO
40
VCC
D.C.
POWER
+ 5V
39
RWISEEK 0
FOO
Read
Write/SEEK: When
"1"
(high) Seek mode selected and
1 RST I
"p
Reset: Places FOe in idle
when
"0"
(low) ReadlWrite
state. Resets output
lines
to
mode selected
FOD
to
"0"
(low)
2
1m
l'
"p
Read: Control signal for
38
LCTIOIR 0 FOO
Low Current/Direction: Lowers
Write
current on inner tracks
transfer
of
data from
FOC
to
In
ReadlWrlte mode, deter·
Data Bus. when
"0"
(low)
mines
direction
head will step
3
WR
l'
"p
Write: Control signal for
in
Seek mode
transfer
of
data
to
FOe
via
Data
37
FAlSTP
0
FOO Fault Reset/Step: Resets fault
Bus, when
"0"
(low)
FF in FOD in ReadlWrite
4 CS I
"p
Chip Select:
Ie
selected
when
"0"
(low), allowing
Ffi)
and m to
be
enabled
mode, provides step puises
to
move head
to
another cylinder
in
Seek mode
5
Ao
I
"p
Data/Status
Reg
Select
Selects
Data Reg
(AO
= 1)
or
Stalus
Reg
(AO
= 0)
36
HOL
0
FOO
Head Load: Command
which
causes read/write head in FDD
to
contact
diskette
content
35
ROY I FOO
Ready: Indicates FDD
Is
ready
be sent
to
Data Bus
to
send
or
receive data
6-13
OBo-OB7
I/O
"p
Data Bus: Bidirectional
34
WPITS
I FOO
Write ProtectlTwo-Slde:
a-Sit
Data Bus
Senses Write Protect status
In
14 ORO 0
OMA
Data DMA Request; DMA
Request is being made
by
ReadIWrlte mode, and Two
Side Media In Seek mode
FOC
when
ORO
"1"
33
FLTITRKO
I FOO
Faultrrrack
0:
Senses FDD
15
OACK
I
OMA
DMA Acknowledge: DMA
cycle
Is active when
"0"
(low) 'and Controller Is
fault
condition
In
ReadlWrlte
mode and Track
0
condition
in Seek mode.
performing
DMA
transfer
31,32
PS"PSO
0
FOO
Precompensatlon (pre-shift):
16
TC
I
OMA
Terminal Count: Indicates
the termination of a DMA
transfer when
"1"
(high)
Write precompensation status
during MFM mode.
Deter·
mines early, late, and normal
times.
17 lOX I
FOO
Index: Indicates the beginning
of
a
disk
track
30
WR
DATA
0
FOO
Write Data: Serial
clock
and
data bits
to
FDD
18
INT
0
"p
Interrupt: 'Interrupt Request
Generated by
FOC
28,29
OS"OSO
0 FOO
Drive Select: Selects FOD
unit
19
CLK
I Clock: Single Phase 8 MHz
Squarewave
Clock
27
HOSEL
0 FOO
Head Select: Head 1 selected
when
"1"
(high) Head 0
selected when
"0"
(low)
20
GNO
Ground:
D.C.
Power Return
26
MFM
0
PLL
MFM Mode: MFM mode when
"1",
FM mode when
"0"
Note
1:
Disabled when CS:
1.
25
WE
0 FOO
Write Enable: Enables write
data
Into
FOD
24
VCO
0
PLL
VCO Sync:
Inhibits
VCO in
PLL when
"0"
(low), enables
VCO when
"1"
23 RO
DATA
I FOO
Read
Data:
Read
data from
FOD,
containing
clock
and
data
bits
22
OW I
PLL
Data Window: Generated by
PLL, and used to sample data
from FDD
21
WRCLK
I
Write Clock: Write data rate
to
FDD
FM
= 500 kHz, MFM = 1
MHz,
with
a pulse
width
of
250
ns for both FM and MFM
9-53
